Wind power installation with multiple blade adjusting devices

ABSTRACT

The present invention concerns a wind power installation having a rotor with at least one blade and an adjusting device for the rotor blade. An adjusting device with more than one drive for one rotor blade is provided. By virtue of that arrangement each drive only has to furnish a corresponding fraction of the power output, it can be of a correspondingly smaller design configuration, and it imposes a correspondingly lower loading on the subsequent components.

TECHNICAL FIELD

The present invention concerns a wind power installation having a rotorwith at least one blade and an adjusting device for the rotor blade.

BACKGROUND OF THE INVENTION

Wind power installations with an adjusting device for the blade havelong been known in the state of the art and are also described in thespecialist literature. Thus for example in the work by Erich Hau in‘Windkraftanlagen’, [‘Wind power installations’], Springer-Verlag, 2ndedition, 1996, pages 231 ff.

That adjusting device must be designed in such a way that it can put therotor blade or, in the case of central rotor blade adjustment, the rotorblades, into a predeterminable position in an acceptable time. For thatpurpose, a drive motor is frequently provided in the state of the art,and that motor must have a minimum power output which is predeterminedby the rotor blades and the loads thereof.

Irrespective of considerations relating to the use and the design oftransmission arrangements, it has been determined by the inventor that,with an increasing size of installation, the rotor blades also becomelarger and therefore the drive motor used for rotor blade adjustmentmust also furnish a higher power output. That higher power outputinevitably results in the drive motor being of larger dimensions.

BRIEF SUMMARY OF THE INVENTION

In accordance with the invention, the adjusting device has at least twodrives. In that way the necessary force for adjustment of the rotorblade or rotor blades can be applied simultaneously at a plurality oflocations to the blade root. Therefore, according to the number ofdrives, each drive acts on the subsequent components only with acorresponding fraction of the overall force required. That in turnpermits those components to be of a smaller design configuration.

In addition, it is possible in accordance with the invention to useavailable drives which are already now available in large numbers andwhich are already tried-and-tested in continuous operation. In addition,apparatuses and methods for the handling thereof are already known andtried-and-tested.

In a particularly preferred embodiment of the invention the drives areelectric motors, more specifically preferably dc motors. In the case ofa fault those electric motors can be connected to an existing emergencypower supply, for example in the form of a battery.

It is also possible to use three-phase asynchronous motors as theelectric motors. To produce a braking torque, those motors, after thethree-phase current flowing during the rotor blade adjustment procedureis switched off, are supplied with a direct current so that a stationarymagnetic field is produced in the asynchronous motors. In that way themotors which are still rotating can be braked and a braking torque ismaintained in the stationary motors.

In regard to the further operating procedure involved in pitchregulation, attention is also to be directed to German patentapplication No 197 31 918.1, which is incorporated herein by referencein its entirety. Insofar as the configurations in the present inventionare concerned, the man skilled in the art would also be able to make useof the structure described therein within the present invention.

Further advantageous embodiments of the invention are set forth in theappendant claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

An embodiment of the invention is described hereinafter with referenceto the accompanying drawings in which:

FIG. 1 is a simplified representation of a rotor blade root with aplurality of drives,

FIG. 2 is a simplified representation of a control according to theinvention, and

FIG. 3 is a simplified representation of a control according to theinvention by means of a dc motor.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows in greatly simplified form a rotor blade root 10, at theperiphery of which are arranged three adjusting drives 12. The rotorblade root 10 itself has an external tooth arrangement 14 at its outerperiphery, which is indicated by a broken line.

The adjusting drives 12 are arranged at uniform spacings at theperiphery of the rotor blade root. The adjusting drives preferablyengage by way of a tooth arrangement a rotary ball connection which isinstalled in the form of a rotary mounting for the rotor blade and byway thereof adjust the rotor blade. Admittedly, it would theoreticallybe basically possible for the adjusting drives also to directly engagethe rotor blade, but under some circumstances that is undesirable as therotor blade root—like also the rest of the rotor blade—comprises glassfibre-reinforced plastic material (GRP) or the like and the fact of theadjusting drives directly engaging in the rotor blade could result indamage to the rotor blade. By virtue of simultaneous operation of allthree drives 12, each drive 12 only has to apply a third of the overallpower output required, which is necessary for adjustment of the rotorblade 10.

In addition, due to the fact that each of the adjusting drives only hasto apply a part, in the specific example illustrated, only a third, ofthe overall force required, the dimensioning thereof can also be smallerthan when only a single adjusting drive 12 is used.

In the event of damage to one of the adjusting drives 12, it can stillbe handled manually, if of suitable dimensions, and can be replaced forexample using a block and tackle, within the pylon of the wind powerinstallation. Alternatively, the drives can be sized such that if one ofthe three fails, the remaining drive 12 or drives 12 have sufficientpower to move the rotor until the failed drive 12 can be repaired.

FIG. 2 shows a control arrangement. The control arrangement has acentral control unit 20 and a plurality of components 22 which can be inthe form of measurement value pick-ups and/or reference value generatorsand/or input means. By way of those components, items of information aremade available to the control unit 20, and from those items ofinformation the control unit 20 derives control data required foractuation of the adjusting drives 12.

Those control data can influence for example a switching device 24 whichsupplies the adjusting drives 12 which are in the form of three-phaseasynchronous motors either with a three-phase current for adjustment ofthe rotor blades 10 or with a direct current for producing a brakingtorque in the adjusting drives 12.

In that way the adjusting drives can exert a braking action in the eventof spontaneous changes in load at the rotor blades, for example withgusty winds which abruptly and briefly change in direction, so thatmeaningful rotor blade adjustment is not possible.

The three adjusting drives 12 are so designed that the further adjustingfunction of the rotor blades can be maintained even if one of the threeadjusting drives fails. The entire wind power installation thereforedoes not have to be shut down if—for whatever reasons—an adjusting driveshould fail, because then the respectively necessary pitch regulationeffect can still be maintained by the two adjusting drives which remain.

If one of the adjusting drives fails, the loads which are then appliedto the two remaining adjusting drives are admittedly greater thanpreviously, but it will be noted that each adjusting drive is sodesigned that it can be operated in an overload mode even for aprolonged period of time. In that respect therefore each individualadjusting drive is somewhat over-sized so that, in the situation whereone of the adjusting drives fails, a drive can still be operated in anoverload mode for a certain period of time in order to initiate a safestop for the wind power installation or to bring the rotor blades intothe feathered position.

FIG. 3 shows by way of example one of the drives 12 which is connectedby way of a relay 24 to the normal operating voltage. In this case therelay 24 is in the working position.

If now a power failure occurs the relay 24 is also de-energised and thecontacts of the relay will switch over and in their rest positionconnect the adjusting drive 12 to the battery 26 so that, in such asituation, movement of the rotor blade into the feathered position andthus stoppage of the installation is reliably and safely possible. Deepdischarge of the battery is tolerated in that case because it is to bepreferred to the installation being in an indeterminate condition, withan unclear rotor blade pitch setting, even though deep discharge of thebattery is not preferred.

1. A wind power installation comprising: a rotor; a rotor blade coupledto the rotor; and an adjusting device for adjusting the pitch angle forthe rotor blade, the adjusting device having at least two electric-motordrives for applying a force for adjustment of the rotor blade at theroot of the rotor blade at different locations for each drive.
 2. A windpower installation according to claim 1 wherein in that the electricdrives are electric dc motors.
 3. A wind power installation according toclaim 1 wherein in that the electric drives are three-phase asynchronousmotors and that the three-phase asynchronous motors are at timessupplied with direct current.
 4. A wind power installation according toclaim 1 wherein by: measuring means for ascertaining the instantaneousloading of at least a part of the wind power installation; and controlmeans which ascertain the position of the rotor blade that is desiredfor greater loading than the current loading, correspondingly adjustsame by means of the adjusting device.
 5. The wind power installationaccording to claim 4, further including means for adjusting the pitch ofthe rotor blade to achieve greater loading.
 6. The wind powerinstallation according to claim 5, wherein said loading level is amaximum possible loading level.
 7. A wind power installation accordingto claim 1, further including: a second rotor blade and wherein in thatat least one rotor blade is adjustable asynchronously with respect tothe other or others.
 8. A wind power installation according to claim 1wherein in that a position of the rotor blade, that is desired for agiven instantaneous loading, can be predetermined by way of input meansconnected to a control means.
 9. A wind power installation according toclaim 1 wherein in that the adjusting device for adjustment of the rotorblade has an adjusting motor and an adjusting transmission driventhereby, wherein a control means receive an actual value relating to aninstantaneous position of the rotor blade, by way of the adjustingdevice.
 10. The wind power installation according to claim 9 furtherincluding means for adjusting.
 11. A wind power installation accordingto claim 1 wherein in that a control means effect adjustment of therotor blade without delay with acquisition of measurement values.
 12. Awind power installation comprising: a rotor; a rotor blade coupled tothe rotor; and an adjusting device for adjusting the pitch angle for therotor blade, the adjusting device having at least two electric-motordrives for applying a force for adjustment of the rotor blade at theroot of the rotor blade at different locations for each drive, whereinat least one portion of the rotor blade is adjustable asynchronouslywith respect to at least one further adjustable portion of the samerotor blade or with respect to the other rotor blade or blades or theportion thereof.
 13. A wind power installation comprising: a rotor; arotor blade coupled to the rotor; and an adjusting device for adjustingthe pitch angle for the rotor blade, the adjusting device having atleast two electric-motor drives for applying a force for adjustment ofthe rotor blade at the root of the rotor blade at different locationsfor each drive, wherein the drives of the adjusting device are coupledto each other.
 14. A wind power installation according to claim 13wherein in that the drives are electrically coupled to each other by atransformer.